Changes in methylmercury accumulation in the brain of rat offspring throughout gestation and during suckling

Higher methylmercury (MeHg) accumulation and susceptibility to toxicity in the fetus than in the mother at parturition is well known. However, the degree of MeHg accumulation in the brain during the late pregnancy period when the human brain is most vulnerable is not clear. In addition, changes in MeHg accumulation in the developing rat tissues with consecutive exposure throughout gestation and lactation periods have not been well studied. The purposes of this study were to evaluate the changes in MeHg accumulation in the brain and other tissues of the offspring, based on constant and consecutive doses of MeHg to mothers throughout gestation and lactation. Adult female rats were given a diet containing 5 ppm Hg (as MeHg) for 8 weeks. Then they were mated and subsequently given the same diet throughout gestation and lactation. On embryonic days 18, 20, 22 and at parturition, the concentrations of Hg in the brains of the offspring were approximately 1.5–2.0 times higher than those in the mothers. On the oth...